JP2001313002A - Discharge lamp, discharge lamp lighting device and illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp, a discharge lamp lighting device and an illumination device using the same having as a main discharge medium a rare gas which has no risk of damaging the illumination device with a low tube wall temperature near an inner electrode, and which is of low driving voltage with little degradation of brightness and flickering of light through suppression of contraction positive column and of a long life with less wear of the inner electrode in life. SOLUTION: The discharge lamp is provided with a discharge vessel 11 composed of a slim translucent airtight vessel 11a, a plurality of inner electrodes 11bA, 11bB sealed into the translucent airtight vessel 11a and a discharge medium with a rare gas as a main ingredient, and a plurality of outer electrodes 12A, 12B arranged at its outer periphery face almost in contact with it which generate discharge inside the discharge vessel 11 between themselves and the corresponding plurality of inner electrodes 11bA, 11bB. The discharge vessel can be in an atypical shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp using a rare gas as a main discharge medium, a discharge lamp lighting device and a lighting device using the same.

2. Description of the Related Art A rare gas fluorescent lamp in which a rare gas such as xenon gas is sealed does not use mercury, which has a large environmental load, and thus has little effect on the environment when disposed. Has the advantage of being hardly affected by

As a fluorescent lamp utilizing rare gas discharge, a xenon fluorescent lamp having a structure as shown in FIGS. 15 and 16 has been developed.

FIG. 15 is a front view showing a first conventional discharge lamp.

FIG. 16 is a front sectional view of the same.

In each of the drawings, reference numeral 1 denotes a straight glass tube having a phosphor layer 2 provided on an inner wall. A discharge medium containing at least xenon is sealed in the glass tube 1. At one end of the glass tube 1, a metal internal electrode 4 is sealed via a supply line 3 for supplying voltage. Glass tube
For example, a metal wire is spirally wound on the outer wall of the outer wall 1 as an external electrode 5 at a predetermined interval along the tube axis direction. As means for fixing the external electrode 5 on the glass tube 1, for example, a light-transmitting tube 6 is provided around the glass tube 1 including the external electrode 5.
Means for coating is adopted. As means for energizing the external electrode 5, a voltage supply line is directly connected to the external electrode 5, or a lead wire 7 sealed at one end of the glass tube 1 so as not to contact the discharge medium as shown in the figure. Or connect through. In the above-described xenon fluorescent lamp, when a driving voltage of the lighting circuit 8 is applied between the internal electrode 4 and the external electrode 5, discharge starts, and ultraviolet light radiated from xenon is converted into visible light by the fluorescent substance. Available as

However, when the above-mentioned fluorescent lamp is turned on, it has been found that there are the following problems.

As shown in FIG. 17, when the diffuse positive column 9 in which the positive column spreads in the radial direction of the tube in almost the entire discharge space in the glass tube is generated, the fluorescent substance is reduced. Brightness can be increased.

FIG. 17 is a front sectional view conceptually showing a diffusion positive column in the first conventional discharge lamp.

However, when the tube current is increased to further increase the luminance of the phosphor, as shown in FIG.
It is called “shrinking positive column”. ), The contracted positive column 9 ′ moves irregularly in the radial direction of the tube, so that the light emission has a flicker of brightness.

FIG. 18 is a front sectional view conceptually showing a contracted positive column in a first conventional discharge lamp.

Since the luminance of the phosphor in the region of the contracted positive column 9 'is several times smaller than that of the diffuse positive column 9, luminance unevenness occurs in the tube axis direction as shown in FIG.

FIG. 19 is a graph showing a luminance distribution along a lamp axis direction when a contracted positive column occurs in a first conventional discharge lamp.

In the figure, the horizontal axis represents the position (cm) in the lamp axis direction, and the vertical axis represents the luminance (cd / m ² ). In the figure, a range a indicates a region of the contracted positive column, a range b indicates a region of the diffused positive column, and a range c indicates the entire length of the discharge lamp.

Therefore, there is a limit to the increase of the tube current,
There is a problem that it is not possible to increase the brightness of the lamp.

Since the contracted positive column 9 'is generated near the internal electrode 4 where the tube current is concentrated, it is necessary to reduce the current density of the positive column near the internal electrode 4.

Short Life There is a problem that the internal electrode 4 is consumed by sputtering during the life because the entire current flows intensively into the internal electrode 4. Also in this case, it is necessary to reduce the amount of current flowing into the internal electrode 4.

High Temperature In addition, since the entire current flows intensively into the internal electrode 4, the tube wall temperature near the internal electrode 4 becomes abnormally high as shown by a curve B in FIG. When a fluorescent lamp is used as a light source for a backlight for a liquid crystal, the lamp current value has an upper limit because the light guide plate disposed near the fluorescent lamp may be thermally damaged.

Increase in driving voltage The above-described xenon fluorescent lamp is used as a backlight source for liquid crystal. However, as the size of the liquid crystal screen increases, the lamp needs to be longer. However, if the lamp length is increased, as shown by the curve D in FIG. 5, the tube voltage required for the discharge to spread over the entire discharge space of the glass tube 1 increases, which causes an increase in the size of the lighting device. .

As means for increasing the amount of light emitted from the lighting device, a lamp of a type in which discharge is performed using one internal electrode 4 and one external electrode 5 is a modified shape other than a linear shape,
For example, as shown in FIG. 20, an L-shaped irregularly shaped fluorescent lamp has been developed.

FIG. 20 is a partially sectional front view showing a second conventional discharge lamp.

In the figure, the same parts as those in FIG.

The fluorescent lamps of these irregular shapes are designed to reduce the number of lamps used as the light source of the illuminating device, and thus have a longer lamp length than a straight tube fluorescent lamp, and as a result, the starting voltage increases. Therefore, there is a problem that the lighting device becomes large. In addition, an increase in the volume of the discharge space causes an increase in the total number of charged particles generated, so that these flow into one internal electrode, thereby increasing the tube current. As a result, flickering and uneven brightness of light emission due to the generation of the contracted positive column, increase in the temperature of the tube wall near the internal electrode, and consumption of the internal electrode during its lifetime are caused.

The present invention has been made in view of the above problems, and has as its object to provide a discharge lamp in which the following items are improved, a discharge lamp lighting device and a lighting device using the same.

1. The driving voltage may be low.

2. The generation of the contracted positive column is suppressed, and the decrease in luminance and the flicker in brightness are small.

3. The life of the internal electrodes during the life is small and the life is long.

4. Since the tube wall temperature near the internal electrode is low,
Less likely to damage lighting equipment.

The present invention also provides a discharge lamp that emits light at a low voltage in almost the entire area of a discharge vessel even when the lamp length is long due to a deformed shape or the like, a discharge lamp lighting device and a lighting device using the same. Other purposes.

[0028]

According to a first aspect of the present invention, there is provided a discharge lamp having an elongated light-transmitting airtight container, a plurality of internal electrodes sealed in the light-transmitting airtight container, and sealed in the light-transmitting airtight container. A discharge vessel that is provided with a discharge medium mainly composed of a rare gas; and a discharge vessel that is substantially in contact with the outer peripheral surface of the light-transmitting airtight container and that is disposed in an insulating relationship with each other and has a corresponding internal electrode. And a plurality of external electrodes capable of causing a discharge inside the discharge vessel.

In the present invention and each of the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified. The following is a description of each component.

<Regarding the Discharge Vessel> The discharge vessel is provided with at least a light-transmitting airtight vessel, a discharge medium, and a plurality of internal electrodes.

(Transparent airtight container) The transparent airtight container is preferably formed by sealing both ends of a glass bulb because it is the easiest to manufacture and the cost is low. It may be formed of optical ceramics or the like. Note that as the glass, soft glass, semi-hard glass, hard glass, quartz glass, or the like can be appropriately selected and used. The fact that the light-transmitting airtight container is light-transmitting does not require that the entire light-transmitting airtight container be light-transmitting, but at least a portion where light generated due to electric discharge is to be derived. Should just be translucent. In addition, that the light-transmitting airtight container is elongated means that the light-transmitting airtight container has a length that is at least twice the outer diameter of the discharge container.

Further, the light-transmitting airtight container may have any of a straight tube shape and a non-straight tube shape, that is, an irregular shape.

Further, in the present invention, the translucent airtight container may have a flat cross section. In this case, the distance from the center to the outer surface portion facing the external electrode is doubled. Diameter.

(Discharge Medium) The discharge medium is mainly composed of a rare gas, and the rare gas is allowed to be xenon, neon, argon, krypton, or the like. Further, in addition to the rare gas, a halide or a simple halogen of the rare gas may be added. As the halogen, iodine, bromine, and chlorine can be used. Discharge is possible if the element exists as vapor in the range of several mHg to several atmospheres.

When a rare gas generates ultraviolet rays by electric discharge like xenon, a phosphor layer which is excited by the ultraviolet rays and generates visible light can be provided on the inner surface side of the transparent airtight container.

(About a plurality of internal electrodes)
A plurality of them are sealed in a translucent airtight container at a distance from each other. For example, in the case of a configuration in which a pair of internal electrodes are sealed, the internal electrodes can be disposed inside both ends of the translucent airtight container. When three or more internal electrodes are sealed, for example, in addition to the above, the internal electrodes can be disposed at an intermediate position of the light-transmitting airtight container.

As the internal electrode, a short electrode of a cold cathode type or a hot cathode type similar to that used for a general internal electrode type discharge lamp can be used.

In order to seal the internal electrode having any of the above structures at the end of the discharge vessel, various known sealing means such as a flare seal, a bead seal, and a pinch seal are appropriately selected and used. Can be.

<Regarding Plurality of External Electrodes> The plurality of external electrodes may have any configuration as long as they are disposed substantially in contact with the outer peripheral surface of the discharge vessel. For example, the external electrode can be constituted by a coil of a conductive material, a cylindrical metal mesh structure, a metal foil, a transparent conductive film, or the like.

Further, the number of the external electrodes is arranged so as to correspond to at least a plurality of internal electrodes. However, it is permissible that the external electrode and the internal electrode face each other, but this is not an essential requirement. Both may be separated by an appropriate distance in the tube axis direction of the discharge vessel.

Further, the external electrode is disposed substantially in contact with the outer peripheral surface of the discharge vessel. Therefore, the external electrode is fixed to the discharge vessel by an appropriate means. For example, it can be fixed by using an adhesive, potting a transparent synthetic resin, or mechanically winding.

<Other Configurations> About Translucent Insulating Tube A translucent insulating tube can be provided outside the external electrode to mechanically fix the external electrode and, if necessary, further improve the insulation of the discharge lamp. The translucent insulating tube is preferably transparent. Further, the light-transmitting insulating tube is preferably heat-shrinkable for the workability of installation.

2. Regarding the phosphor layer As described above, when the rare gas emits ultraviolet rays by discharge and uses visible light, the phosphor layer can be disposed on the inner surface side of the translucent airtight container. . When the discharge lamp is used for a backlight, a phosphor emitting white light such as a phosphor of a three-wavelength emission type or a halophosphate phosphor is preferable.
For reading, a phosphor that emits green light is preferable. In short, the color of the phosphor may be selected according to the application of the discharge lamp.

Further, the phosphor layer may be formed on the entire peripheral surface of the light emitting region in the longitudinal direction of the discharge vessel, or a light guide slit in which the phosphor layer is not formed in the tube axis direction to form an aperture structure. You can also.

3. About a protective film etc. If necessary, a protective film or an electron emitting material film made of alumina fine particles or the like can be formed on the inner surface of the translucent airtight container. When forming a protective film, a protective film may be formed between the phosphor layer and the inner surface of the translucent airtight container, or a protective film may be formed on the inner surface of the phosphor layer on the discharge space side. Is also good.
In addition, an electron emitting material film can be formed, and in this case, it is effective to avoid or reduce the occurrence of dark characteristics of the discharge lamp.

<Regarding the Operation of the Present Invention> The present invention has the above-described structure, and has a plurality of internal electrodes and a plurality of external electrodes provided with a common translucent airtight container. In order to light this discharge lamp, a lighting circuit may be connected between one internal electrode and one corresponding external electrode. Then, the respective lighting circuits are similarly connected between the other internal electrodes and the external electrodes. For this reason,
One translucent airtight container emits light as if a plurality of discharge lamps were connected in series. As a result, the following operation and effect can be obtained.

1. For a given length of translucent airtight container, one external electrode can be shortened,
The drive voltage applied between the corresponding internal electrode and external electrode is reduced. In other words, a discharge lamp having a large tube length can be driven with a low drive voltage.

2. The lamp current flowing into one internal electrode can be reduced. For this reason, the generation of the contracted positive column can be suppressed. Therefore, it is possible to prevent a decrease in luminance and a flicker in brightness due to the occurrence of the contracted positive column.

3. As the lamp current flowing into one internal electrode can be reduced, the consumption of the internal electrode during lighting due to sputtering of the internal electrode can be reduced. Therefore, the life of the discharge lamp can be extended.

4. As the lamp current flowing into one internal electrode can be reduced, the temperature near the internal electrode decreases. Therefore, it is possible to prevent damage to the lighting device using the discharge lamp as a light source, for example, to prevent heat damage to the light guide plate of the liquid crystal backlight device.

The discharge lamp according to the second aspect of the present invention is the first aspect.
In the above-described discharge lamp, the discharge vessel is characterized by having an irregular shape.

In the present invention, the “irregular shape” means that the shape of the discharge vessel in the longitudinal direction is not a straight pipe shape. Examples of irregular shapes include L-shape, U-shape,
Various shapes such as a U-shape, a W-shape, a ring shape, and a semi-annular shape can be adopted. Further, not only the above-described two-dimensional shape but also a three-dimensional arbitrary curve can be obtained. further,
In order to form an irregular shape, after heating a straight tube-shaped glass tube, it can be curved by applying an external force, or can be curved using a molding die.

Thus, in the present invention, since the discharge vessel is of an irregular shape, a single discharge lamp is configured to simultaneously enter the light guide plate of a backlight device for a liquid crystal from two or more sides thereof, for example. It becomes possible. That is, the discharge lamp that performs rare gas discharge has a smaller amount of light than the discharge lamp that performs mercury vapor discharge, so it is necessary to lengthen the discharge vessel to increase the amount of light. Therefore, it is conceivable to arrange a plurality of discharge lamps in a straight tube shape on a plurality of end faces of the light guide plate to compensate for the insufficient light amount.
This configuration increases the cost and
It becomes difficult to incorporate the discharge lamp into the backlight device, for example, in terms of wiring and supporting the discharge lamp.

On the other hand, in the present invention, the discharge vessel is made long and has an irregular shape so that one discharge lamp can simultaneously receive light from a plurality of end faces without increasing the driving voltage. can do. For this reason, the cost can be reduced, and the incorporation into the backlight device becomes easy.

On the other hand, by increasing the discharge vessel without increasing the driving voltage, the amount of light emission can be increased, so that higher luminance can be obtained than when a single straight tube-shaped discharge lamp is used.

Thus, in the present invention, it is possible to use various discharge modes such as simultaneously inputting light from a plurality of end faces of the light guide plate with one discharge lamp, thereby achieving cost reduction.

The discharge lamp according to the third aspect of the present invention is the second aspect of the present invention.
The discharge lamp as described, wherein the discharge vessel has a curved portion in the middle of the longitudinal direction; the plurality of external electrodes are spaced apart such that the curved portion of the discharge vessel is located between at least one pair thereof. Are characterized;

In the present invention, the discharge vessel has an irregular shape having a curved portion in the middle in the longitudinal direction. The term “bent portion” is used as a concept that includes both a state in which the discharge vessel is bent in a gentle curve and a state in which the discharge vessel is sharply bent, that is, a so-called bent state. As the irregular shape, for example, a locus tracing the center position of the lamp cross-section along the tube axis direction, such as an L-shape, a U-shape, a U-shape, a V-shape, or a W-shape, simulates an alphabet or katakana character. The shape shown in the figure is allowed. In this case, it is sufficient that the character shape can be recognized in a pseudo manner even if the angle, shape, or the like of the lamp bending portion is slightly changed.

By the way, the above-described discharge lamp having a different shape generally utilizes light emission from a straight tube portion, and light emission from a curved portion does not significantly affect the brightness of the lighting device.

Thus, in the present invention, since the curved portion of the discharge vessel is located between at least one pair of the plurality of external electrodes, the external electrode can be disposed avoiding the curved portion. Is easy to arrange. Moreover, there is no problem in the light emission distribution.

Further, since no discharge occurs in the curved portion of the discharge vessel, wasteful power consumption is eliminated and the efficiency of the lighting device is increased.

Further, since the curved portion of the discharge vessel is located between the pair of external electrodes, a required insulation distance can be provided between the external electrodes.

The discharge lamp according to the fourth aspect of the present invention is the first aspect of the present invention.
In the discharge lamp described above, the external electrode is formed by a coil made of a conductive material.

The coil made of a conductive material may be formed using a metal wire, or a conductive material may be applied to the outer peripheral surface of the discharge vessel.
It may be formed by vapor deposition or printing. When a coil is formed using a metal wire, the coil can be arranged by directly winding the metal wire around the discharge vessel, or by inserting a coil preformed using a springy metal wire into the discharge vessel. .

Further, the coil made of a conductive material can be arranged in the discharge vessel with its pitch being constant or changing. When the pitch is reduced, the luminance of the part increases, and when the pitch is increased, the luminance of the part decreases. On the other hand, as the position on the external electrode moves away from the internal electrode, the brightness at that position decreases. The light distribution along the longitudinal direction of the discharge vessel is flattened by making the coil pitch relatively denser as the distance from the internal electrode is increased, and conversely by decreasing the coil pitch as the distance from the internal electrode is increased. Can be controlled in various directions. However, if necessary, even when it is desired to obtain a non-uniform luminance distribution in the tube axis direction, the pitch of the coil of the external electrode can be appropriately changed.

Further, the coil can be fixed to the discharge vessel by partially bonding both ends of the coil of the metal wire to the discharge vessel with an adhesive. When the adhesive is opaque or low opaque, it is partially, that is, spot-shaped, at both ends of the coil and at positions where the light distribution characteristics of the discharge lamp are less affected. An adhesive may be applied to fix the coil. On the other hand, when the coil is fixed at an intermediate position, a translucent, preferably transparent adhesive is preferably used. Of course, it is needless to say that a light-transmitting adhesive can also be used when applied to the end of the coil. However, alternatively or additionally, the coil can be fixed to the discharge vessel by tightly winding the winding start portion for a few turns.

Further, the coil made of a conductive material preferably has a resistivity of 2 × 10 ⁻⁴ Ω / cm or less from the viewpoint of reducing the power loss of the external electrode. For example, the resistivity can be reduced by using Ni, Cu, or the like. The cross-sectional shape of the conductive material may be a ribbon, a circle, an ellipse, a semicircle, a rectangle, a polygon such as a triangle or a trapezoid, or a shape imitating them, or a thin film formed by a printing method or the like. Is also good.

Next, the power receiving means of the external electrode will be described.

One end of the coil can be directly led out to receive power from the external electrode. Instead, it is embedded in one end of the translucent airtight container, but seals the external lead in a state where it is not exposed to the discharge space, and solders one end of the coil to this external lead, It can be connected by caulking or welding.

Thus, in the present invention, the use of a coil made of a conductive material for the external electrode has the following effects.

1. The area of the external electrode in the radial direction of the discharge vessel can be reduced. Thereby, light loss blocked by the external electrode can be reduced,
Therefore, the lamp efficiency of the discharge lamp is improved.

2. By changing the coil pitch,
The brightness of that part can be controlled. Therefore, the light emission distribution of the discharge lamp can be controlled.

According to a fifth aspect of the present invention, there is provided a discharge lamp lighting device,
A discharge lamp according to any one of claims 1 to 4, and a plurality of lighting circuits respectively connected between each internal electrode and each corresponding external electrode.

The structure of the discharge lamp lighting device suitable for lighting the above-described discharge lamp of the present invention is defined.

That is, as the lighting circuit, it is preferable to use a power supply that outputs a high-frequency AC voltage having a waveform such as a rectangular wave or a sine wave, or a pulse voltage having a high repetition frequency. Note that the pulse voltage can be obtained by half-wave rectification of a high-frequency AC voltage of a rectangular wave or a sine wave.

A plurality of lighting circuits can be easily obtained, for example, by arranging a plurality of secondary windings in an output transformer of a common high-frequency inverter.

According to a sixth aspect of the present invention, there is provided a lighting device, comprising: a lighting device main body; and a discharge lamp lighting device according to the fifth aspect disposed in the lighting device main body.

In the present invention, the “illumination device” is a broad concept including all devices utilizing the light emission of a discharge lamp, and includes, for example, a backlight unit, a liquid crystal display device having the same, and a liquid crystal display device incorporating the same. Including equipment. Equipment incorporating a liquid crystal display device, for example,
Examples include devices incorporating a liquid crystal display device, such as personal computers, navigation devices, portable information terminals, and liquid crystal television receivers, as well as instrument panel lighting devices for vehicles, such as automobiles, and decorative lighting devices.

The “illumination device main body” refers to the remaining portion of the illumination device excluding the discharge lamp.

[0080]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing a first embodiment of the discharge lamp of the present invention.

FIG. 2 is a front vertical sectional view showing a first embodiment of the discharge lamp and the discharge lamp lighting device of the present invention.

In each figure, 11 is a discharge vessel, 12A,
12B is first and second external electrodes, 13 is a light-transmitting insulating tube, and 14A and 14B are first and second lighting circuits.

<Regarding the Discharge Vessel 1>
Transparent airtight container 11a, first and second internal electrodes 11
bA, 11bB, internal introduction line 11c, external introduction line 11
d and the phosphor layer 11e.

The light-transmitting hermetic container 11a is made of, for example, an elongate glass bulb made of hard glass having an outer diameter of 1.6 to 10 mm, a thickness of 0.1 to 0.7 mm, and a length of 50 to 700 mm. Has an elongated discharge space 11a
1 is formed.

First and second internal electrodes 11bA and 11bA
bB is made of, for example, a cold cathode having a cylindrical shape made of a Ni-based alloy having an inner diameter of about 2.0 mm and a length of about 4 mm with an open end, and is supported by welding at the end of an internal introduction line 11c made of Kovar to transmit light. It is sealed at one end in the airtight container 11a.

The external introduction line 11d is made of Kovar wire, is formed by integrally extending the internal introduction line 11c, and is sealed at both ends of the translucent airtight container 11a.
The base end extends from the translucent airtight container 11a to the outside.

The phosphor layer 11e is made of a phosphor of a three-wavelength emission type, and has a discharge space 11a1 in a translucent airtight container 11a.
Are formed in almost all regions of the intermediate portion except for both ends of.

The discharge space 11a1 of the hermetic container 11a is filled with a rare gas mainly composed of xenon.

<First and Second External Electrodes 12A, 12A
Regarding B> In the present embodiment, the first and second external electrodes 12A and 12B are each formed of a coil formed using a metal wire. The coil is 0.05-0.4m in diameter
m, Ni, Cu or other metal wire at a pitch of 0.1 to 10 mm
The inner surface of the discharge vessel 1
1 is in contact with the outer peripheral surface.

The external electrodes 12A and 12B are arranged at a distance of about 5 mm from one end of the light-transmitting airtight container 11a and leaving a central portion. Then, the first external electrode 1
2A corresponds to the first internal electrode 11bA. Similarly, the second external electrode 12B corresponds to the second internal electrode 11bB.

<Regarding the Insulating Tube 13> The insulating tube 13 is formed by shaping a transparent heat-shrinkable resin sheet made of a fluororesin having a thickness of about 0.1 to 2.5 mm into a tube shape. The discharge vessel 11 is covered from the outside of the external electrodes 12A and 12B, and is shrunk by heating to bring the first and second external electrodes 12A and 12B into contact with the outer peripheral surface of the discharge vessel 11 and fixed to form a discharge lamp. ing.

<First and second lighting circuits 14A, 14A
Regarding B> The first lighting circuit 14A is connected between the first external electrode 12A and the first internal electrode 11bA. Similarly, the second lighting circuit 14B includes the second external electrode 1
It is connected between 2B and the second internal electrode 11bB.
Then, the first and second lighting circuits 14A and 14B
They are mainly composed of high-frequency inverters, each of which outputs a drive voltage with a high repetition frequency of a rectangular wave.

<Operation of Discharge Lamp> When a required driving voltage is applied from the first lighting circuit 14A between the first internal electrode 11bA and the first external electrode 12A of the discharge lamp, both electrodes 11bA are turned on. , 12A, a dielectric barrier discharge occurs in the left half region in the figure in the discharge space 11a1, and xenon of the enclosed discharge medium emits ultraviolet rays. Similarly, when a required driving voltage is applied from the second lighting circuit 14B between the second internal electrode 11bB and the second external electrode 12B, the discharge voltage in the discharge space 11a1 located between the two electrodes 11bB and 12B is increased. In the figure, a dielectric barrier discharge occurs in the right half area, and xenon of the discharge medium enclosed therein emits ultraviolet rays. For this reason, a discharge occurs in the entire region in the discharge space 11a1, and the ultraviolet rays irradiate the phosphor layer 1e, so that the phosphor is excited and emits visible light. The emitted visible light is applied to the external electrodes 12A and 12A.
Since it is led out from the gap formed between each turn of the coil B to the outside from the entire circumference, visible light can be used as a lighting device.

FIG. 3 is a graph showing the luminance distribution along the tube axis direction in the first embodiment of the discharge lamp of the present invention.

In the figure, the horizontal axis represents the position (cm) in the lamp axis direction, and the vertical axis represents the luminance (cd / m ² ). In the figure, the range c is the entire length of the lamp, the dotted line d is the center of the lamp,
Are respectively shown.

As can be understood from comparison between FIG. 19 and FIG. 19, in this embodiment, the obtained luminance distribution is uniform.

FIG. 4 is a graph showing the tube wall temperature distribution along the tube axis direction in the first embodiment of the discharge lamp of the present invention together with that of the comparative example.

In the figure, the horizontal axis is the distance (cm) from one internal electrode side lamp end, the vertical axis is the luminance (cd / m ² ),
Are respectively shown. The comparative example is a discharge lamp having the structure shown in FIG. In the figure, a curve A indicates the present embodiment, and a curve B indicates a comparative example. A straight line e indicates one end of the discharge lamp, and a straight line f indicates the center of the discharge lamp.

As can be understood from the drawing, in this embodiment, the tube wall temperature is substantially uniform along the tube axis direction.
On the other hand, in the comparative example, the tube wall temperature near the portion facing the internal electrode is extremely high.

FIG. 5 is a graph showing the output voltage of the power supply when the discharge spreads over the entire area of the discharge lamp according to the first embodiment of the present invention, together with that of the comparative example.

In the figure, the horizontal axis represents the lamp length (mm), and the vertical axis represents the output voltage (Vp-p) of the power supply when the discharge spreads over the entire area of the lamp. The comparative example is shown in FIG.
Is a discharge lamp having the structure shown in FIG. Also, "power"
It means a lighting circuit. In the figure, a curve C indicates the present embodiment, and a curve D indicates a comparative example.

As can be understood from the drawing, in this embodiment, a discharge lamp having a long lamp length and a low output voltage can be obtained. On the other hand, in the comparative example, a long lamp length cannot be used, and a high output voltage is required.

Hereinafter, another embodiment of the external electrode in the discharge lamp of the present invention will be described with reference to FIGS. In the figure, the same parts as those in FIG.

FIG. 6 is a partially sectional front view and a lateral end view showing a second embodiment of the discharge lamp of the present invention.

In this embodiment, the external electrode 12 is made of a metal foil, and is adhered to the outer surface of the discharge vessel 11. The metal foil is, for example, an aluminum foil, and a material adhered to a transparent resin thin plate substrate can be used.

FIG. 7 is a partially sectional front view and a lateral end view showing a third embodiment of the discharge lamp of the present invention.

In this embodiment, the external electrode 12A is made of a transparent conductive film, and is formed on the outer surface of the discharge vessel 11 by vapor deposition, chemical vapor deposition (CVD), or the like.

FIG. 8 is a partial sectional front view and a lateral end view showing a fourth embodiment of the discharge lamp of the present invention.

In the present embodiment, the external electrode 12 is formed of a metal mesh structure, and is mounted on the outer peripheral surface of the discharge vessel 11. The metal mesh structure is formed in a cylindrical shape, into which the discharge vessel 11 is inserted and fixed. If the metal mesh structure is a knitted structure, the diameter can be reduced by pulling both ends, and the metal mesh structure can be brought into close contact with the discharge vessel 11.

Next, an embodiment of a discharge lamp according to the present invention in which a discharge vessel has an irregular shape will be described with reference to FIGS. 9 to 12, together with a discharge lamp lighting device. In the figure, FIG.
The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted.

FIG. 9 is a front view showing a fifth embodiment of the discharge lamp of the present invention together with a lighting circuit.

In this embodiment, the discharge vessel 11 has an L-shape.

That is, the discharge vessel 11 has a curved portion 11a2 in the middle, and a pair of long and short straight tube portions 11a3 and 11a4 arranged at right angles on both sides thereof. The first and second internal electrodes 11bA and 11bB are sealed at both ends of the discharge vessel 11, and the corresponding first and second external electrodes 12A and 12B are disposed on the straight pipe portions 11a3 and 11a4. . Further, the first and second external electrodes 12A, 12A,
2B indicates that the coil pitch is the same as that of the internal electrodes 11bA and 11bB.
The side changes relatively sparsely and the other side changes densely. Thereby, consideration is made so that the luminance distribution in the straight pipe portions 11a3 and 11a4 is as uniform as possible.

First and second lighting circuits 14A and 14B
Is adjusted in voltage waveform and phase so as to generate a diffused positive column that can increase the luminance of the phosphor. Further, each output voltage value is used to set the first and second external electrodes 12A, 12A,
It is set at a ratio corresponding to the length of 2B (the length of the shared light emission range), and the first and second internal electrodes 11
When a discharge occurs between aA and 11aB, a contracted positive column having a low luminance of the phosphor is generated in the entire tube and causes a decrease in luminance and a flicker in brightness. Therefore, the voltage difference between the internal electrodes is maintained so as not to discharge. Have been.

Thus, the present embodiment is suitable for a case where light enters from two adjacent sides of a rectangular light guide plate.

FIG. 10 is a front view showing a sixth embodiment of the discharge lamp of the present invention together with a lighting circuit.

In this embodiment, the discharge vessel 11 has a U-shape.

That is, the discharge vessel 11 has two curved portions 11a2, 11a2 in the middle, and three long and short straight tube portions 11a3, 11a4 arranged on both sides and in the middle at right angles.
11a5. First and second internal electrodes 1
1 bA and 11 bB are sealed at both ends of the discharge vessel 11. First external electrode 12 corresponding to internal electrode 11bA
A is disposed over the straight pipe portions 11a3 and 11a5. Also, the second internal electrode 11bB corresponding to the second internal electrode 11bB
The external electrode 12B is disposed on the straight pipe portion 11a4.

Therefore, the first external electrode 12A has a large number of turns in the coil, and the pitch of the coil in the opposite side to the internal electrode 11bA, particularly in the linear portion 11a5, is high, and the straight tube portion 11a3 of the entire discharge lamp is provided. , 11a4, 1
Care is taken to make the luminance distribution of 1a5 as uniform as possible. Note that the drive voltage of the lighting circuit 14A is set to be higher as the number of turns of the external electrode 12A is larger.

Thus, the present embodiment is suitable for a case where light enters from three sides of a rectangular light guide plate.

FIG. 11 is a front view showing a seventh embodiment of the discharge lamp of the present invention together with a lighting circuit.

In this embodiment, the discharge vessel 11 has a U-shape.

That is, the discharge vessel 11 has one curved portion 11a2 having a large curvature in the middle, and a pair of straight pipe portions 11a3 and 11a4 of the same length disposed in parallel on both sides thereof. First and second internal electrodes 11bA, 11bA
bB is sealed at both ends of the discharge vessel 11 as in the above embodiments. First and second internal electrodes 11b
A and first and second external electrodes 12 corresponding to 11bB
A and 12B have the same change in the number of turns and the change in pitch.

Thus, this embodiment is suitable for a so-called direct type backlight device in which light enters from the bottom surface of a rectangular diffusion plate.

FIG. 12 is a front view showing an eighth embodiment of the discharge lamp of the present invention together with a lighting circuit.

In this embodiment, the discharge vessel 11 has a double U-shape.

That is, the discharge vessel 11 has three curved portions 11a2, 11a2, 11a2 having a large curvature in the middle,
And four straight pipe portions 11a6 adjacent thereto. In addition to the first and second internal electrodes 11bA and 11bB, a third internal electrode 11bC is provided at the center in the longitudinal direction of the translucent airtight container 11a. Correspondingly, in addition to the first and second external electrodes 12A and 12B, the third
Are provided. Third external electrode 1
2C is disposed over the third internal electrode 11bC.

On the other hand, in the lighting circuit, the first
A third lighting circuit 14C is provided in addition to the second lighting circuits 14A and 14B. Since both ends of the third external electrode 14C are connected to the third lighting circuit 14C, the third external electrode 14C functions as a pair of external electrodes that are divided into two with respect to the internal electrode 11bC and connected in parallel.

Thus, the present embodiment is suitable for a so-called direct type backlight device in which light is incident from the bottom surface of a rectangular diffusion plate requiring a large area or high luminance.

FIG. 13 is a partially sectional plan view showing a backlight device for a liquid crystal as one embodiment of the lighting device of the present invention.

FIG. 14 is a lower side view of the same.

In the figure, reference numeral 21 denotes a backlight body, 2
2 is a discharge lamp.

The backlight device main body 21 includes a light guide 21.
a, a reflection case 21b, a reflection sheet 21c, a diffusion sheet, a lens sheet, a protection sheet and the like 21d and the like,
It is stored in a case (not shown). The light guide 21a is formed of a square transparent body having a high refractive index, such as a transparent acrylic resin or a polycarbonate resin. The reflection case 21b reflects light emitted from the discharge lamp 22 in a direction that does not directly enter the light guide 21a and causes the light to enter the light guide 21a.
Shield so as not to leak light to places other than a. The reflection sheet 21c is disposed on the bottom surface of the light guide plate 21a and
The light that is going to go to the bottom side of a is reflected to the top side. A diffusion sheet, a lens sheet, a protection sheet, and the like 21d are appropriately combined and disposed on the upper surface of the light guide 21c according to the application, and improve the brightness and uniformity of the backlight.

The discharge lamp 22 has the structure shown in FIG. 9, and is arranged so that light enters from the end faces of two adjacent sides of the light guide plate 21a. Therefore, the same parts as those in FIG. 9 are denoted by the same reference numerals.

[0136]

According to the first to fourth aspects of the present invention, a plurality of internal electrodes are sealed in an elongated light-transmitting airtight container, a light-transmitting airtight container, and a discharge medium mainly containing a rare gas is sealed. And a plurality of external electrodes disposed substantially in contact with the outer peripheral surface of the discharge vessel and configured to generate a discharge inside the discharge vessel between the corresponding plurality of internal electrodes. Thereby, a discharge lamp having the following effects can be provided.

1. The driving voltage may be low.

[0138] 2. The generation of the contracted positive column is suppressed, and the decrease in luminance and the flicker in brightness are reduced.

[0139] 3. The life of the internal electrodes during the life is small and the life is long.

4. Since the tube wall temperature near the internal electrode is low,
Does not damage lighting equipment.

According to the second aspect of the present invention, in addition, since the discharge vessel has a deformed shape, a single discharge lamp can simultaneously enter the light guide plate from the end faces of a plurality of sides without increasing the driving voltage. It is possible to provide a discharge lamp that can be used in various applications such as light emission to reduce costs and that can be easily incorporated into a lighting device.

According to the third aspect of the present invention, the discharge vessel has a curved portion in the middle in the longitudinal direction, and is disposed so as to be spaced such that the curved portion of the discharge vessel is located between at least one pair of the plurality of external electrodes. Since the external electrodes can be arranged avoiding the curved portion by being provided, the arrangement of the external electrodes is easy, and no discharge occurs in the curved portion of the discharge vessel, so that unnecessary power consumption is eliminated. In addition, it is possible to provide a discharge lamp in which the efficiency of the lighting device is increased.

According to the fourth aspect of the present invention, since the external electrode is formed by a coil made of a conductive material, the area of the external electrode in the radiation direction of the discharge vessel is reduced, so that the light blocked by the external electrode is reduced. It is possible to provide a discharge lamp that controls the light emission distribution by changing the coil pitch while reducing the loss and improving the lamp efficiency.

According to a fifth aspect of the present invention, there is provided a discharge lamp lighting device including a plurality of lighting circuits respectively connected between the internal electrodes and the corresponding external electrodes according to the first to fourth aspects. be able to.

According to claim 6 of the present invention, claims 1 to 5
It is possible to provide a lighting device having the above-mentioned effect.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a discharge lamp of the present invention.

FIG. 2 is a front vertical sectional view showing a first embodiment of a discharge lamp and a discharge lamp lighting device of the present invention.

FIG. 3 is a graph showing a luminance distribution along a tube axis direction in the first embodiment of the discharge lamp of the present invention.

FIG. 4 is a graph showing a tube wall temperature distribution along a tube axis direction in a first embodiment of the discharge lamp of the present invention together with that of a comparative example.

FIG. 5 is a graph showing the output voltage of the power supply when the discharge spreads over the entire lamp in the first embodiment of the discharge lamp of the present invention, together with that of the comparative example.

FIG. 6 is a partial sectional front view and a lateral end view showing a second embodiment of the discharge lamp of the present invention.

FIG. 7 is a partially sectional front view and a lateral end view showing a third embodiment of the discharge lamp of the present invention.

FIG. 8 is a partial sectional front view and a lateral end view showing a fourth embodiment of the discharge lamp of the present invention.

FIG. 9 is a front view showing a fifth embodiment of the discharge lamp of the present invention together with a lighting circuit.

FIG. 10 is a front view showing a sixth embodiment of the discharge lamp of the present invention together with a lighting circuit.

FIG. 11 is a front view showing a seventh embodiment of the discharge lamp of the present invention together with a lighting circuit.

FIG. 12 is a front view showing an eighth embodiment of the discharge lamp of the present invention together with a lighting circuit.

FIG. 13 is a partial cross-sectional plan view showing a liquid crystal backlight device as one embodiment of the illumination device of the present invention.

FIG. 14 is a lower side view of the same.

FIG. 15 is a front view showing a conventional first discharge lamp.

FIG. 16 is a front sectional view of the same.

FIG. 17 is a front sectional view conceptually showing a diffusion positive column in a first conventional discharge lamp.

FIG. 18 is a front sectional view conceptually showing a contracted positive column in a conventional first discharge lamp.

FIG. 19 is a graph showing a luminance distribution along a tube axis direction when a contracted positive column is generated in a first conventional discharge lamp.

FIG. 20 is a partial cross-sectional front view showing a second conventional discharge lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Discharge container 11a ... Translucent airtight container 11a1 ... Discharge space 11bA ... 1st internal electrode 11bB ... 2nd internal electrode 1c ... Internal introduction line 1d ... External introduction line 1e ... Phosphor layer 12A ... 1st outside Electrode 12B: second external electrode 13: translucent insulating tube 14A: first lighting circuit 14B: second lighting circuit

Claims (6)

[Claims] 1. A light-transmitting airtight container having an elongated shape, a plurality of internal electrodes sealed in the light-transmitting airtight container, and a discharge medium mainly containing a rare gas sealed in the light-transmitting airtight container. A plurality of discharge vessels, which are substantially in contact with the outer peripheral surface of the light-transmitting airtight vessel and are disposed in an insulating relationship with each other to generate a discharge inside the discharge vessel between the corresponding internal electrodes. A discharge lamp comprising: an external electrode; 2. The discharge lamp according to claim 1, wherein the discharge vessel has an irregular shape. 3. The discharge vessel has a curved portion in the middle in the longitudinal direction; the plurality of external electrodes are spaced apart such that the curved portion of the discharge vessel is located between at least one pair thereof. The discharge lamp according to claim 2, wherein: 4. The discharge lamp according to claim 1, wherein the external electrode is formed by a coil made of a conductive material. 5. A discharge lamp according to claim 1, comprising: a plurality of lighting circuits respectively connected between each internal electrode and each corresponding external electrode. Discharge lamp lighting device characterized by the above-mentioned. 6. A lighting device comprising: a lighting device main body; and the discharge lamp lighting device according to claim 5 disposed in the lighting device main body.